HP procurve 2500 사용자 설명서

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Fast-Uplink Spanning Tree Protocol (STP)

When single-instance spanning tree (STP) is running in a network and a forwarding port goes down, 
a blocked port typically requires a period of

(2 x (forward delay) + link down detection) 

to transition to forwarding. In a normal spanning tree environment, this transition is usually 30 
seconds (with the 

 parameter set to its default of 15 seconds). However, by using the fast-

uplink spanning tree feature, a port on a Switch 2512 or 2524 used as an edge switch can make this 
transition in as little as ten  seconds. (In an STP environment, an edge switch is a switch that is 
connected only to switches that are closer to the STP root switch than the edge switch itself, as shown 
by switch "4" in figure 68, below.) 

In figure 68, STP is enabled and in its default configuration on all switches, unless otherwise indicated  
in table 11, below:

With the above-indicated topology and configuration: 

■

 If the link between switches "4" and "2" goes down, then the link between 

switches "4" and "3" will begin forwarding in as little as ten seconds.

■

 If Switch "1" fails, then:

•

Switch "2" becomes the root switch.

•

The link between Switch "3" and Switch "2" begins forwarding.   

•

The link between Switch "2" and the LAN begins forwarding.

Switch Priority

0

1

1

2

32,768 (default)

32,768 (default)

(Fast) Uplink

No

No

No

Ports 3 & 5

1

This setting ensures that Switch "1" will be the primary root switch for STP in figure 68.

2

This setting ensures that Switch "2" will be the backup root switch for STP in figure 68.

Switch 

4

Switch 

3

Switch 

1

Switch 

2

     Port 3

      Port 5

Link blocked by STP: 

1

6

8

LAN